Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/96—Regeneration, reactivation or recycling of reactants
  • B01D53/965—Regeneration, reactivation or recycling of reactants including an electrochemical process step
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/86—Catalytic processes
  • B01D53/8696—Controlling the catalytic process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
  • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
  • B01D53/9495—Controlling the catalytic process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/0006—Controlling or regulating processes
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
  • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
  • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
  • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
  • C01B3/38—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/10—Noble metals or compounds thereof
  • B01D2255/102—Platinum group metals
  • B01D2255/1021—Platinum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/10—Noble metals or compounds thereof
  • B01D2255/102—Platinum group metals
  • B01D2255/1023—Palladium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/40—Mixed oxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/40—Nitrogen compounds
  • B01D2257/404—Nitrogen oxides other than dinitrogen oxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/50—Carbon oxides
  • B01D2257/502—Carbon monoxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
  • B01D2257/702—Hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/10—Catalysts for performing the hydrogen forming reactions
  • C01B2203/1041—Composition of the catalyst
  • C01B2203/1082—Composition of support materials
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/16—Controlling the process
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/32—Hydrogen storage
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

• the present invention relates to a control system for catalytic processes.
• the present invention further relates to a control system for in processes for reforming hydrocarbon streams and for pollution remediation of exhaust streams.
• Catalyst systems are employed extensively to reform light hydrocarbon streams, i.e. reduce methane and other light hydrocarbons to hydrogen, and to remediate exhaust streams, i.e. reduce/oxidize internal combustion exhaust to innocuous compounds.
• a problem encountered with catalyst systems is poisoning of the catalyst.
• One source of such poisoning is adsorption/infiltration of oxygen- containing species such as carbon monoxide. Carbon monoxide interferes with the catalysis mechanism.
• Another source of poisoning is the deposition of carbon.
• Methods of addressing catalyst poisoning include applying to the catalyst a direct current (DC) electric field and/or heating it to an elevated temperature, i.e. about 300°C to about 800°C. Most commonly, an electric field and heat are concurrently applied.
• DC electric field and heat expels or pumps oxygen-containing molecular species from the catalyst.
• Application of DC current and/or heat to catalysts is described in the following: U.S. Patent/Application Nos. 2001/0000889 A1; 2002/0045076 A1; 4,318,708; 5,006,425; 5,232,882; 6,214,195; and 6,267,864.
• a problem encountered with application of a DC electric field to catalyst systems is a lack of a means for monitoring and sensing the level of poisoning present in the catalyst in real time or on a continuous basis. This lack of means to monitor and sense the level of poisoning in the catalyst in real time hinders precise and timely application of DC electric fields. Precise and timely application of DC electric field is important because if the field is too weak, the rate of expulsion of oxygen-containing species may be too low and such species may accumulate. If the DC field is too strong, the incidence of catalytically effective sites in the catalyst may be reduced.
• the application of heat to catalyst systems also has the problem lack of real time control means but also suffers from imprecise effects of temperature on catalyst behavior and physical structure. If the temperature of the catalyst is too low, the catalyst may become fouled (dirty) and the kinetics of the catalyzed reaction may be negatively altered. If the temperature is too high, the kinetics of the catalyzed reaction may be negatively altered and/or the microstructure of the catalyst destroyed.
• control system for a catalytic process.
• the control system comprises the following: a) an electroconductive support having a layer of a catalyst thereon; b) a means for applying DC current of one polarity to the catalyst layer and the opposite polarity to the electroconductive support; c) a means for controlling and varying the application of DC current; d) a means for measuring the polarization impedance across the catalyst layer and the electroconductive support; e) a means for comparing the measured polarization impedance with a reference value; and f) a means for varying the application of DC current to the catalyst layer and the electroconductive support when the measured polarization impedance differs from the reference value.
• the control system may further optionally comprise the following: g) a means for heating the electroconductive support; h) a means for controlling and varying the application of heat; and i) a means for varying the application of heat to the catalyst and the electroconductive support when the measured polarization impedance differs from the reference value.
• control system for a catalytic process.
• the control system has an electroconductive support having a layer of a catalyst thereon.
• a current control unit communicates with a first electrode and a second electrode opposite in polarity to the first electrode.
• the current control unit controls and varies the application of DC current to the first and second electrodes.
• the first electrode is in contact with the electroconductive support.
• the second electrode is in contact with the catalyst.
• the current control unit controls and varies the application of an AC current to the first and second electrodes.
• An AC sensor is in communication with the catalyst layer or the electroconductive layer.
• the level of AC current in the first and second electrodes and the level of AC current detected at the AC sensor at two different frequencies is communicated to an impedance measurement unit where polarization impedance is determined.
• the impedance measurement unit communicates with a central processing unit wherein the measured polarization impedance is compared to a reference value.
• the central processing unit communicates with the current control unit to vary the application of DC current to the first and second electrodes when the determined polarization impedance differs from the reference value.
• control system for a catalytic process.
• the control system has a) first and second system components each having an electroconductive support having a catalyst layer thereon wherein the catalyst layers are spaced-apart from, in proximity to, and oriented toward each other; b) a means for applying a DC field across the two catalyst layers; c) a means for controlling and varying the application of the DC field; d) a means for measuring the polarization impedance across the two catalyst layers; e) a means for comparing the measured polarization impedance with a reference value; and f) a means for varying the application of the DC field across the two catalyst layers when the measured polarization impedance differs from the reference value.
• control system for a catalytic process.
• the control system has first and second system components each having an electroconductive support having a catalyst layer thereon wherein the catalyst layers being spaced-apart from, in proximity to, and oriented toward each other.
• a current control unit communicates with a first electrode and a second electrode opposite in polarity to the first electrode.
• the current control unit controls and varies the application of DC current to the first and second electrodes.
• the first electrode contacts the first system component and the second electrode contacting the second system component.
• An AC sensor communicates with the second system component.
• the current control unit communicates with the AC sensor and controls and varies the application of AC current to the first and second electrodes.
• the level of AC current in the first and second electrodes and the level of AC current detected at the AC sensor at two different frequencies is communicated to an impedance measurement unit where polarization impedance is determined.
• the impedance measurement unit communicates with a central processing unit wherein the measured polarization impedance is compared to a reference value.
• the central processing unit communicates with the current control unit to vary the application of DC current to the first and second electrodes when the measured polarization impedance differs from the reference value.
• FIG. 1 is a schematic diagram of a control system in accordance with the present invention.
• Figure 2 is a schematic diagram of a control system wherein two catalyst layers are oriented toward each other.
• Figure 3 is a schematic diagram of a control system wherein the catalyst layer is cylindrical in shape.
• the present invention provides an in situ means for detecting the level of poisoning in a catalyst and means for maintaining precise control of the application of a DC electric field and, optionally, heat (temperature) thereto.
• Catalyzed reaction conditions can be optimized for maximum conversion of reactant chemical species and/or selection of certain reaction pathways and products.
• the DC current can be set to maximize the number of catalytically effective sites in the catalyst, if desired.
• the reaction temperature of the catalyzed reaction can be set to maximize reaction rate and/or select certain reaction pathways and products and prevent poisoning/fouling of the catalyst.
• the in situ sensor employs alternating current (AC) at variable frequency and is connected along the same circuit as the direct current.
• the sensor continuously monitors the state of the catalyst by measuring impedance in a three point arrangement. The higher the concentration of oxygen-containing species or poisoning species like carbon monoxide in the catalyst, the higher the polarization component of the impedance.
• the sensor communicates with a central processing unit (CPU), which communicates with the control mechanisms regulating the voltage of DC current applied and, optionally, the amount of heat applied.
• CPU central processing unit
• Polarization impedance is the difference between impedance measured at low and high frequencies of alternating current.
• Polarization impedance can be calculated according to the following formulas I and II:
• i cor r steady state corrosion current
• ⁇ a Tafel constant for aniodic reaction
• ⁇ c Tafel constant for cathodic reaction
• Test frequencies will vary depending on the characteristics and requirements of the system, but suitable low frequencies typically range from about 0.1 Hz to about 100 Hz and suitable high frequencies typically range from about 10 kilohertz to about 5 megahertz.
• Polarization impedance is typically expressed in ohm. The method for calculating polarization impedance is set forth in Applications of Impedance Spectroscopy, J. Ross McDonald, p. 262, John Wiley & Sons (1987), which is incorporated herein by reference.
• impedance generally corresponds to the difference or drop in AC current across a catalyst layer/electroconductive support, which will vary in structure depending upon the structure of the catalyst system.
• the difference in AC current will usually be between the first electrode/second electrode and the AC sensor.
• the polarization impedance is obtained when the impedance is measure at a low and a high frequency.
• Control system 10 has an electroconductive support 12 and a catalyst layer 14 situated thereon.
• a current control unit 28 communicates with and controls and provides DC current to a first electrode 1 and a second electrode 18 through current cables 20.
• First electrode 17 is contiguous to and in electrical contact with electroconductive support 12.
• Second electrode 18 is contiguous to and in electrical contact with catalyst layer 14.
• Current control unit 28 also controls and provides AC current to first electrode 7 and second electrode 18 through current cables 22.
• a polarization impedance measurement unit 26 communicates with AC sensors 16, which are contiguous to and electrical contact with catalyst layer 14 through data transmission cables 24.
• Control system 10 also has a heater 36 and a heating control unit 34.
• Heating control unit 34 communicates with heater 36 through an interface 7 and a data transmission cable 24.
• the current control unit 28, polarization impedance measurement unit 26, and heating control unit 34 communicates with and are controlled by a central processing unit 32 through interface 7.
• the process throughput such as a hydrocarbon stream or combustion exhaust will contact catalyst layer 14 as it impinges or otherwise traverses it.
• Electrodes may take any electroconductive form, but usually take the form of an electrically conductive wire or conduit contacting catalyst layer 14 or support 12.
• a Solartron 1260 (Solartron Co.) can carry out all control and measurement functions, including current control, central processing unit, provision of direct and alternating current, and impedance measurement.
• Control system 40 is two component assemblies 41 and 43.
• Component assembly 41 has an electroconductive support 46, a catalyst layer 46, and a heater 54.
• Component assembly 43 has an electroconductive support 44, a catalyst layer 48, and a heater 56.
• a current control unit (not shown) communicates with and controls and provides both AC and DC current to a first electrode 58 and a second electrode 60 through current cables 50.
• First electrode 58 is contiguous to and in electrical contact with electroconductive support 42.
• Second electrode 60 is contiguous to and in electrical contact with catalyst layer 44.
• a polarization impedance measurement unit (not shown) communicates with AC sensor 62, which is contiguous to and electrical contact with catalyst layer 46 through data transmission cable 52.
• Heaters 54 and 56 are controlled by a heating control unit (not shown). When control system 40 is in operation, the process throughput such as a hydrocarbon stream or combustion exhaust will contact catalyst layers 46 and 48 as it passes between them.
• Control system 70 is essentially tubular or cylindrical in configuration (not shown).
• Figure 3 is a cross-section view of that control system of essentially tubular or cylindrical configuration.
• Control system 70 is adapted to function to function to transport, process, and serve as a catalytic reactor for process throughput such as a hydrocarbon stream or combustion exhaust.
• Control system 70 may be placed within tubing, piping, or other conduit if desired.
• control system 70 is shown to have an electroconductive support 72, a catalyst layer 74, and heaters 86 and 88.
• a current control unit (not shown) communicates with and controls and provides both AC and DC current to a first electrode 76 and a second electrode 78 through current cables 84.
• First electrode 76 is contiguous to and in electrical contact with electroconductive support 72.
• Second electrode 78 is contiguous to, embedded in, and in electrical contact with catalyst layer 74.
• a polarization impedance measurement unit (not shown) communicates with AC sensor 80, which is contiguous to, embedded in, and electrical contact with catalyst layer 74 through data transmission cable 82.
• Heaters 86 and 88 are controlled by a heating control unit (not shown).
• the catalyst layer is typically maintained at a temperature of about 100°C to about 800°C.
• the temperature of the catalyst layer may be elevated to higher levels, e.g. up to about 1060°C, for a period of time sufficient for the polarization impedance to fall to the desired level.
• the temperature of the catalyst layer will be elevated for about 1 minute or more.
• the present invention is useful in reforming feedstocks containing methane and other light hydrocarbons, e.g. ethane, propane, and butane, to elemental hydrogen (H 2 ). This process is particularly useful in fuel cells.
• methane and other light hydrocarbons e.g. ethane, propane, and butane
• elemental hydrogen (H 2 ) This process is particularly useful in fuel cells.
• the present invention is also useful in remediating pollution, i.e. converting gaseous pollutants to innocuous compounds.
• pollution i.e. converting gaseous pollutants to innocuous compounds.
• NO x nitrous oxides
• N 2 elemental nitrogen
• CO carbon monoxide
• CO 2 carbon dioxide
• HC Hydrocarbons
• the electroconductive support may be any material upon which a catalyst can be deposited and that is electrically conductive to a sufficient degree. Suitable materials include solid electrolytes, mixed conductors, and cermets. Examples of solid electrolytes include oxygen ion conductors, solid solutions, and proton conductors. Examples of oxygen ion conductors include stabilized zirconia, stabilized bismuth oxide, yttria- stabilized bismuth oxide, and Nb Os-stabilized bismuth oxide, sodium beta alumina, hydronium beta alumina, and porous metals. Examples of solid solutions include those of CaTiO 3 , SrTiO 3 , and LaAIO 3 . A useful proton conductor is National (E.I. duPont de Nemours & Co.). An example of a mixed conductor is cerium oxide based solid solutions. An example of a cermet is molybdenum suicide.
• the electroconductive support may take any shape or configuration known in the art such a disk or other planar surface, a hollow cylinder, or a honeycomb.
• the catalyst may be selected from any known to be useful in reforming hydrocarbon feedstocks or remediating pollution.
• Useful catalysts include metals or electrically conductive ceramics.
• Useful metals include platinum and palladium.
• Useful ceramics include SnO-ln 2 O 3 mixtures.
• the catalyst may be deposited on a surface of the electroconductive support by any technique known in the art such as painting, electrophoresis, and gas-vapor deposition. Such techniques will typically be followed by a thermal or electrochemical treatment for attaining the desired coverage factor, porosity and degree of physical contact with the support.
• the catalyst may be deposited on any or all surfaces of the support.
• the heat source may employ any means of generating heat know in the art such as electricity, gas, oil, or other fuel.
• the heat source is located in proximity to and preferably contiguous to the electroconductive support and/or catalyst layer.
• the heat source provides heat to the support and, in turn, via conduction to the catalyst layer.
• Heat may be provided by any or all of the modes of conduction, convection, and/or radiation.
• Some portion of heat may be provided to the catalyst layer by process throughput such as the hydrocarbon feedstock or combustion exhaust if such throughput exhibits an elevated temperature.
• any heat provided by process throughput would be augmented or supplemented by the heat source.
• hydrocarbon feedstocks or pollution streams may be passed through gas filtration media to remove contaminants prior to contact with the catalyst.
• gas filtration media can help maintain the integrity of the catalyst and lengthen its service life.
• Useful filtration media includes woven and non-woven varieties of paper, fabric, plastic, and other synthetic materials as well as metal grate and open-cell foams.
• the present invention may also be employed in conjunction with control systems that employ electromagnetic radiation to maintain effectiveness of the catalyst system as described above.
• the same means for measuring polarization impedance could be employed across an electroconductive support having a catalyst surface thereon as described above.
• electromagnetic radiation of certain type, energy and/or frequency could be applied to the catalyst surface.
• the present invention is also useful for certain military applications.
• the catalyst system may be employed to oxidize and/or reduce nerve gases/liquids, poisons, or other toxins to inert or innocuous compounds.
• the catalyst system may be employed in gas masks or in breathing, aeration, ventilation systems, and the like.
• the catalyst system may be useful in aeration/ventilation systems for battlefield vehicles such as tanks and armored personnel carriers.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Environmental & Geological Engineering (AREA)
• Health & Medical Sciences (AREA)
• Analytical Chemistry (AREA)
• Organic Chemistry (AREA)
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• Oil, Petroleum & Natural Gas (AREA)
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• 2003
  • 2003-04-25 US US10/423,376 patent/US7325392B2/en not_active Expired - Fee Related
  • 2003-11-04 JP JP2004571465A patent/JP4502818B2/ja not_active Expired - Fee Related
  • 2003-11-04 AU AU2003290609A patent/AU2003290609A1/en not_active Abandoned
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